A Little Note on Douban API

Overview

Douban is a popular Chinese social cultural site. It integrates Book reading, movie criticism, city events, and miniblog together.
From my past couple day’s experience, though most Chinese social websites open their API, but they all have different ‘tricks’ to successfully send your http post and get commands. I had been confused on Douban’s photo uploading format for a while, and now I was hoping to share the points you should be careful when uploading your photo using urllib and urllib2 libraries from python.

Encode your photo

The format to encode the photo to pass to Douban could be very restrict. The following format works:

------------0x14026e4be72\r\n
Content-Disposition: form-data; name="text"\r\n\r\nDraw\r\n------------0x14026e4be72\r\n
Content-Disposition: form-data; name="image"; filename="hidden"\r\n
Content-Length: 2019551\r\n
Content-Type: image/jpeg\r\n
Content-Transfer-Encoding: binary\n\r\n
YOUR_IMAGE BYTES
\r\n------------0x140297140d1\r\nContent-Disposition: form-data; name="source"\r\n\r\nYOUR_APP_KEY\r\n------------0x140297140d1--\r\n

Things you should really keep in mind is that Douban needs a clear declaration of Content-Type, you need to restrictedly follow the format. Use mimetypes.types_map would return you a dictionary of types they have, and you could pass your uploading file’s extension as a key into mimetypes.types_map.get(YOUR_FILE_EXTENTION), and it should return you the correct answer for Content-Type.
Also, 0x14026e4be72 is just the boundary variable you could generate randomly.

Following is the python code:
test_douban class

import gzip, time, urllib, urllib2, mimetypes

def _encode_multipart(**kw):
    ' build a multipart/form-data body with randomly generated boundary '
    boundary = '----------%s' % hex(int(time.time() * 1000))
    data = []
    for k, v in kw.iteritems():
        data.append('--%s' % boundary)
        if hasattr(v, 'read'):
            # file-like object:
            filename = getattr(v, 'name', '')
            content = v.read()
            data.append('Content-Disposition: form-data; name="%s"; filename="hidden"' % k)
            data.append('Content-Length: %d' % len(content))
            data.append('Content-Type: %s' % _guess_content_type(filename))
            data.append('Content-Transfer-Encoding: binary\n')
            data.append(content)
        else:
            data.append('Content-Disposition: form-data; name="%s"\r\n' % k)
            data.append(v.encode('utf-8') if isinstance(v, unicode) else v)
    data.append('--%s--\r\n' % boundary)
    return '\r\n'.join(data), boundary

def _guess_content_type(url):
    n = url.rfind('.')
    if n==(-1):
        return 'application/octet-stream'
    ext = url[n:].lower()
    # mimetyeps.types_map keys are stored in lower case, ex: '.jpeg'
    return mimetypes.types_map.get(ext, 'application/octet-stream')

This version of code is heavily depends on the existed code from internet. I just amended little bit on the encoding part to make the format be accepted by Douban.

call test_douban class

from test_douban import _encode_multipart
import urllib2
import urllib
url = 'https://api.douban.com/shuo/v2/statuses/'
access_token = YOUR_ACCESS_TOKEN
fh = open(PATH_TO_YOUR_IMAGE_FILE,'rb')
status = THINGS_YOU_WANT_TO_SAY
params = {'text':status, 'image':fh, 'source':YOUR_APP_KEY}
coded_params, boundary = _encode_multipart(**params)
# after previews call, you have the encoded photo, and a random generated boundary
req = urllib2.Request(url, data=coded_params)
req.add_header('Accept-Encoding', 'gzip')
req.add_header('Authorization', 'Bearer %s' % access_token)
req.add_header('Content-Type', 'multipart/form-data; boundary=%s' % boundary)
resp = urllib2.urlopen(req)

Now you should see the photo you just post on Douban’s miniblog. Cheers !

July 28, 2013

C J

A Little Note on Douban API

Overview

Encode your photo

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